The present invention relates to bumpers for passenger vehicles designed to reduce pedestrian injury upon impact, and more particularly relates to a bumper having an energy absorber optimized to provide a relatively soft initial impact and a “throwing” force after initial impact to a pedestrian struck by the bumper.
Automotive bumper systems in the United States have been designed for resistance to damage at low and high vehicle speeds and for high-energy absorption at high impact speeds. Recently, pedestrian safety has begun to receive increasing attention. However, design of bumpers for pedestrian safety is complicated by several conflicting functional requirements. Obviously, the human body cannot withstand high-energy impacts nor sharp impacts without substantial damage to muscle and bone tissue. However, it is difficult to reduce the magnitude and rate of energy transfer from a bumper to a pedestrian upon impact, especially immediate transfer of energy from a “sharp” impact, because vehicle bumpers are usually limited to a relatively short stroke by components behind the bumper, such as a radiator and other engine components, and also limited by other front-end components and supporting structure. This is especially true of smaller and more compact vehicles. Further, the bumpers must be made of strong materials in order to maintain their shape and appearance over time, and to provide their primary function of being a “bumper” for the vehicle to push away items and to prevent damage to the vehicle. The problems are further complicated by aerodynamic designs, where corners of the bumper system are swept and curved back into the vehicle fenders, which further limits bumpers strokes and the bumper's ability to collapse or flex. Also, the problem is compounded by the fact that bumpers are at knee-height, such that pedestrian-related vehicular accidents often involve trauma to the pedestrian's knees. Joints and exposed bones are particularly prone to injury upon impact.
Accordingly, a bumper system is desired solving the aforementioned problems and having the aforementioned advantages.